This website uses cookies to deliver some of our products and services as well as for analytics and to provide you a more personalized experience. Click here to learn more. By continuing to use this site, you agree to our use of cookies. We've also updated our Privacy Notice. Click here to see what's new.

This website uses cookies to deliver some of our products and services as well as for analytics and to provide you a more personalized experience. Click here to learn more. By continuing to use this site, you agree to our use of cookies. We've also updated our Privacy Notice. Click here to see what's new.

About Optics & Photonics TopicsOSA Publishing developed the Optics and Photonics Topics to help organize its diverse content more accurately by topic area. This topic browser contains over 2400 terms and is organized in a three-level hierarchy. Read more.

Topics can be refined further in the search results. The Topic facet will reveal the high-level topics associated with the articles returned in the search results.

Abstract

This work reports both experimental and theoretical studies on the InGaN/GaN light-emitting diodes (LEDs) with optical output power and external quantum efficiency (EQE) levels substantially enhanced by incorporating p-GaN/n-GaN/p-GaN/n-GaN/p-GaN (PNPNP-GaN) current spreading layers in p-GaN. Each thin n-GaN layer sandwiched in the PNPNP-GaN structure is completely depleted due to the built-in electric field in the PNPNP-GaN junctions, and the ionized donors in these n-GaN layers serve as the hole spreaders. As a result, the electrical performance of the proposed device is improved and the optical output power and EQE are enhanced.

Figures (7)

Fig. 1 Schematic diagrams of the studied devices (Reference LED without ITO coating and PNPNP-GaN LED without ITO coating), shown along with the band diagram of one PNP-GaN junction in the PNPNP-GaN LED.

Fig. 2 (a) Equivalent circuit of an InGaN/GaN LED grown on an insulating substrate (e.g., sapphire) with lateral current-injection scheme (I1 > I2 > I3 > I4 > ..... > In), and (b) a simplified equivalent circuit of this InGaN/GaN LED with possible current paths (J1 and J2) when a PNPNP-GaN current spreading layer is embedded. ITO is not used in these two devices.

Fig. 3 Liner-plot of experimentally measured current as a function of the applied voltage for (a) Reference LED without ITO coating and PNPNP-GaN LED without ITO coating (along with a semi-log plot inserted in the inset) and (b) Reference LED with ITO coating and PNPNP-GaN LED with ITO coating (again with a semi-log plot given in the inset).

Fig. 5 (a) Experimentally measured optical output power and EQE as a function of the current injection, and (b) numerically simulated optical output power and EQE as a function of the current for Reference LEDs without and with ITO coatings and PNPNP-GaN LEDs without and with ITO coatings.

Fig. 7 (a) Equivalent circuit of an InGaN/GaN LED grown on an insulating substrate (e.g., sapphire) using ITO top coating with lateral current-injection scheme (I1 > I2 > I3 > I4 > ..... > In), and (b) a simplified equivalent circuit of this InGaN/GaN LED with possible current paths (J1 and J2) when a PNPNP-GaN current spreading layer is embedded, along with additional ITO film used as the transparent current spreading layer on the top.